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| {{Template:Op menubar}} | | {{Template: Op menubar}} {{Template:Doc_menubar}} |
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| [[Category:Operations Manuals]]
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| {{TOC_right}}
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| {{Ops_procedures | | {{DeprecatedAndMovedTo|new_location=https://docs.egi.eu/providers/operations-manuals/man07_voms_replication}} |
| |Doc_title = VOMS Replication | |
| |Doc_link = [[MAN07|https://wiki.egi.eu/wiki/MAN07]]
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| |Version = 28 lis 2011
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| |Policy_acronym = OMB
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| |Policy_name = Operations Management Board
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| |Contact_group = Alessandro Paolini
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| |Doc_status = Approved
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| |Approval_date =
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| |Procedure_statement = This manual provides information on how to implement a MySQL VOMS server replication.
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| }} | |
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| == Introduction ==
| | [[Category:Operations_Manuals]] |
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| In this manual we will show you how to implement a MySQL VOMS server replication: you need one master server, on which you can perform writing operations, and you can have from 1 to "n" replica servers that will work in read-only mode. In such a scenario you can do a whatever intervention on one of the servers without breaking the service, i.e. proxies creation and grid-mapfile downloads: just the users registration and the usual VOs management operations might be forbidden during an intervention on the master server (because it is the only server in writing mode).
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| This failover procedure is simply based on mysql replication therefore every mysql setting is referred to the current mysql version (5.0.77 in this moment)
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| == Settings on the MASTER SERVER ==
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| In order to allow the replica server to read the master database, you have to create an user with which the slave will connect to the master.
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| Suppose the replica hostname is vomsrep.cnaf.infn.it, the user is bonjovi and the password is always: what you have to launch on the master server is
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| mysql -p -e "grant super, reload , replication slave, replication client on *.* to bonjovi@'vomsrep.cnaf.infn.it' identified by 'always'" ;
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| Then for each DB (VO) you want to replicate, you have to assign the right permissions, by launching:
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| mysql -p -e "grant select, lock tables on voms_myvo.* to bonjovi@'vomsrep.cnaf.infn.it'"
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| Eventually you have to modify the file ''/etc/my.cnf'' by adding the following lines into the section "[mysqld]":
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| log-bin=mysql-bin
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| server-id=1
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| innodb_flush_log_at_trx_commit=1
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| sync_binlog=1
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| It is important that on the master server it is set "server-id=1": it is the identification number that distinguish a master from its several slaves (each slave will have a unique number starting from 2)
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| For example, the content of my.cnf file may appear like this:
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| # less /etc/my.cnf
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| [mysqld]
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| datadir=/var/lib/mysql
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| socket=/var/lib/mysql/mysql.sock
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| user=mysql
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| # Default to using old password format for compatibility with mysql 3.x
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| # clients (those using the mysqlclient10 compatibility package).
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| old_passwords=1
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|
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| max_connections = 800
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| log-bin=mysql-bin
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| server-id=1
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| innodb_flush_log_at_trx_commit=1
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| sync_binlog=1
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| # Disabling symbolic-links is recommended to prevent assorted security risks;
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| # to do so, uncomment this line:
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| # symbolic-links=0
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| [mysqld_safe]
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| log-error=/var/log/mysqld.log
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| pid-file=/var/run/mysqld/mysqld.pid
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| At this point, you have to restart mysql, by launching:
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| service mysqld restart
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| In order to check that on the master side the mechanism is working, you can launch for example:
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| mysql> show master status;
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| +------------------+----------+--------------+------------------+
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| | File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
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| +------------------+----------+--------------+------------------+
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| | mysql-bin.000001 | 24844 | | |
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| +------------------+----------+--------------+------------------+
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| 1 row in set (0.00 sec)
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| Eventually, through the web interface, in the ACL section of each VO you want to replicate, add an entry granting all the permissions to the slave server:
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| * select "a non VO member" from the menu
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| * fill in the replica server DN and a reference email address
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| * select "all" for the permissions and tick the "Propagate entry to children contexts" option
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| In this way, when the slave server copies the DB, it will have the proper permissions on acting on the DB.
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| Morover, in order to avoid the sending of notification to the email address you filled in before, connect to the mysql DB and do the following:
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| mysql> use voms_myvo;
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| mysql> update admins set email_address=NULL where email_address="what you filled before";
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| == Settings on the SLAVE SERVER ==
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| Install a VOMS server as usual, configuring the VOs you want to replicate: keep in mind that every modification done on the slave DB breaks the replica mechanism, so that on this server disable the users registration, by setting the yaim variable
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| VOMS_ADMIN_WEB_REGISTRATION_DISABLE=true
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| and therefore ask the VO managers to not perform any action on the slave server web interface.
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| Then launch the following scripts:
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| *[[VOMS Replication first replica|first_replica.sh]] for the first database you want to replicate or in the case it is the only one
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| *[[VOMS Replication next replicas|next_replicas.sh]] for the next databases (one database for each launch)
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| For both the scripts, set the following variables:
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| *master_host, master_mysql_user, master_mysql_pwd that refers to the master server and to the user created on it
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| *mysql_username_admin e mysql_password_admin that refers to the slave
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| EXAMPLE:
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| voms_database="" # VOMS database (leave unset)
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| master_host="voms.cnaf.infn.it" # Master hostname
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| master_mysql_user="bonjovi" # Master MySQL admin user for replication
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| master_mysql_pwd="always" # Master MySQL admin pass for replication user
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| master_log_file="" # Master LOG file (leave unset)
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| master_log_pos="" # Master LOG file (leave unset)
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| mysql_username_admin="root" # Slave MySQL admin username
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| mysql_password_admin="secret" # Slave MySQL admin pass
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| with the launch of first-replica.sh, the file /etc/my.cnf will be properly written; if you need to replicate further databases, modify /etc/my.cnf adding the following lines related to the db you are replicating (similar to the first db you've replicated):
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| replicate-do-db=<master_vo_db_name>
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| replicate-ignore-table=<master_vo_db_name>.seqnumber
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| replicate-ignore-table=<master_vo_db_name>.realtime
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| replicate-ignore-table=<master_vo_db_name>.transactions
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| replicate-ignore-table=<slave_vo_db_name>.seqnumber
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| replicate-ignore-table=<slave_vo_db_name>.realtime
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| replicate-ignore-table=<slave_vo_db_name>.transactions
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| Having set the variables in the way shown above, for replicating the first database the scripts launch syntax is the following:
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| ./first_replica.sh --master-db=voms_myvo --db=voms_myvo
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| In your /etc/my.cnf file you will find lines like the following:
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| # Connection with master
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| server-id=2
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| master-host=voms.cnaf.infn.it
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| master-user=bonjovi
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| master-password=always
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|
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| # Replicas settings
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| replicate-do-db=voms_myvo
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| replicate-ignore-table=voms_myvo.seqnumber
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| replicate-ignore-table=voms_myvo.realtime
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| replicate-ignore-table=voms_myvo.transactions
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| replicate-ignore-table=voms_myvo.seqnumber
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| replicate-ignore-table=voms_myvo.realtime
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| replicate-ignore-table=voms_myvo.transactions
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| now you may want to replicate a second database, let's say voms_hervo: therefore in my.cnf file add the following lines:
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| replicate-do-db=voms_hervo
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| replicate-ignore-table=voms_hervo.seqnumber
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| replicate-ignore-table=voms_hervo.realtime
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| replicate-ignore-table=voms_hervo.transactions
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| replicate-ignore-table=voms_hervo.seqnumber
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| replicate-ignore-table=voms_hervo.realtime
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| replicate-ignore-table=voms_hervo.transactions
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| modify the script next_replicas.sh in according to the VO parameters and launch it:
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| ./next_replicas.sh --master-db=voms_hervo --db=voms_hervo
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| when you finished to replicate all the desired VOs, in order to make active the database modifications, restart voms and voms-admin:
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| /etc/init.d/voms-admin stop
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| /etc/init.d/voms stop
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| /etc/init.d/voms start
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| /etc/init.d/voms-admin start
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| Keep in mind that every modification done on the slave DB breaks the replica mechanism, so that on this server disable the users registration, by setting the yaim variable:
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| VOMS_ADMIN_WEB_REGISTRATION_DISABLE=true
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| and ask the VO managers to not perform any action on the slave server web interface
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| == Revision History ==
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| {| border="3"
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| ! Version!! Authors !! Date !! Comments
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| |-
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| ! 1.0
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| | Alessandro Paolini
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| | 2011-10-14
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| | First Draft
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| |-
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The wiki is deprecated and due to be decommissioned by the end of September 2022.